The present invention relates to support structures and more particularly to methods and apparatus relating to support structures incorporating load bearing fabric as a load bearing surface.
Load bearing fabric continues to gain an increasing share of the market for load bearing surfaces. Load bearing fabrics have a variety of desirable characteristics. For example, load bearing fabrics provide a durable, high strength load bearing surface that is attractive and easily maintained. The characteristics of load bearing fabrics can be tuned to provide, among other things, a surface that is well-suited for use in seating and other body support applications.
Experience has revealed that it can be difficult to manufacture load bearing fabric structures by directly molding the fabric to support structure. Typically, the type of materials required to withstand the loads applied to the load bearing structure are not well-suited for direct molding with the load bearing fabric. For example, the mold conditions required to mold the frame material could damage the load bearing fabric. To address this problem, the load bearing fabric in many applications is mounted to a support frame using a “carrier.” The carrier is an intermediate component that is manufactured from a material that is more suitable for direct molding with the load bearing fabric. Accordingly, the carrier may be molded in place on the fabric to provide a structure that can be mounted to the support frame. The use of a separate carrier increases the manufacturing and assembly cost of the structure. For example, the use of a separate carrier requires an additional mold and, during manufacture requires time and effort to manufacture the carrier and attach it to the frame.
As technology relating to load bearing fabrics and associated structural counterparts continued to improve, it become possible to more consistently and uniformly mold the frame in place directly on the fabric. In conventional manufacturing systems of this type, the fabric extends fully through the mold cavity and its peripheral edge is held outside the mold cavity, for example, by the mold itself or by a stretching assembly located outside mold. Although these manufacturing systems overcome some of the problems associated with the use of a separate carrier, the excess fabric used to hold the fabric must be trimmed from the load bearing structure. This results in waste fabric and can leave a visible trim line around the load bearing structure.
Accordingly, there remains a need for an improved apparatus and method for manufacturing a load bearing fabric structure in which the frame is molded in place directly onto the fabric.